Vertical air compliant hemming head

ABSTRACT

The present invention pertains to a hemming head for performing a hemming operation which comprises a support housing adapted for securement to a robot arm on a first end, and having a first roller rotatably secured to a second end. The first roller has a cylindrical body, a head, and a groove between the body and head. The head has a diameter greater than the body, and the groove has a diameter less than the body. The groove also includes a canted surface that conjoins with the head. In use, the cylindrical body is adapted to engage and force a workpiece edge downwardly to a first position and the canted surface is adapted to engage and force the workpiece from the first position to a second position.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 61/209,931, which was filed on Mar. 12, 2009, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hemming sheet metal and more particularly to a hemming apparatus and method for forming a generally flat hem between two metal panels. Even more particularly, this invention relates to a roller-type hemming apparatus for edge hemming vehicle closure panels, such as hemming door, hood, trunk, and deck lid panels.

2. Description of the Prior Art

In the automotive industry, hemming machines are conventionally used to attach two metal panels together. These metal panels include, for example, the metal panels to form the automotive hood, door panels, quarter panels, and the like.

Hemming machines are disclosed in the patent prior art, including U.S. Pat. Nos. 5,267,387, issued Dec. 7, 1993 to Sawa; 6,425,277, issued Jul. 30, 2002 to Wiens; 6,983,633, issued Jan. 10, 2006 to Holmgren et al.; and 7,152,447, issued Dec. 26, 2006 to Toeniskoetter; and U.S. Patent Publication No. 2005/0229666, published Oct. 20, 2005 to Toeniskoetter.

A conventional roller hemming apparatus is mounted to a multi-axis controllable robot and may include a hem roller carried by a support. The roller hemming apparatus is adapted for hemming a bent portion of a workpiece, such as a door panel, which is positioned on a hemming die. The workpiece is hemmed by rolling the hem roller, under pressure, along the bent portion. The conventional roller-type hemming apparatus is used for continuous hemming along the contour edge of the workpiece.

In order to achieve good hemming with a conventional hemming apparatus, the robot must move the hem roller along the edge of the workpiece at a constant distance from the hemming die. However, a robot is not comprised of a perfectly rigid body. Therefore, when the hem roller is positioned against the edge of the workpiece, the robot may be deflected by its own resiliency or by a resistive force exerted by the edge of the workpiece itself. This results in a fluctuation of the pressing force applied by the hem roller onto the edge of the workpiece, and therefore imperfect hemming of the workpiece.

Various approaches to compensate for fluctuating pressing force have been proposed. For example, springs have been used. However it has been observed that springs alone have proven to be inadequate.

In addition, traditional hemming rollers having a single roller only enable the user to hem simplistic workpiece such as those having open areas. However single roller hemming apparatuses are not capable of hemming a workpiece with complex configurations.

Additionally, certain workpieces having complex geometry may be difficult to hem. It is costly to reconfigure robot-controlled hemming apparatuses because it is time consuming with respect to labor expenses. In addition, customized tooling required to reconfigure the mounting of the robot is expensive. To overcome this problem, some roller hemming apparatuses provide two rollers on a common spindle. The first roller is used for the actual hemming, while the second roller is used to guide the first roller relative to the workpiece.

Additionally, as work progresses, oftentimes the circumference of the hemming roller may become nicked, thus resulting in an imperfect hemming.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for hemming a pair of panels together. In each, a robot controlled arm causes a roller-type hemming apparatus to hem a pair of upturned flanges together as a result of hemming rollers of the apparatus accurately following the configuration of the bent portion of a workpiece to be hemmed.

In a preferred embodiment of a method according to this invention, there is disclosed a method for roller hemming together the upturned edges of at least two metal panels to form an edge hemmed panel assembly, the steps of the method comprising:

positioning the upturned edges in mated faced engagement on a support frame, the upturned edge of the first metal panel engaging the upturned edge of the second metal panel and forming a flange portion that extends across and beyond the mated upturned edge of the second metal panel;

providing a hemming apparatus having a first and a second roller and a break plate associated with the first roller, each roller being disposed on a roller carriage and capable of completing a finished edge hem in successive passes of relative motion of the rollers along the length of the mated edges of the metal panels wherein the flange portion of the first metal panel is folded over in a gradual bend from one end to another of the mated edges to effectively engage the flange portion with the outer side of the mated edge portion of the second panel and thereby maintain the panels in an assembly; and

manipulating the hemming apparatus in a manner that the first roller and break plate engage opposite sides of the first panel and form a fulcrum break line that facilitates bending of the flange portion over the mated edge portion of the second metal panel and are then moved away from the flange portion followed by the second roller engaging and forcing the flange portion toward and into engagement with the second metal panel.

According to this method, the first roller and the break plate operate on opposite sides of the upturned flanges and, in a single pass, fold or bend the upwardly ending flange portion downwardly toward the panel assembly to be at an acute angle to the upturned edge of the first panel. The break plate is disk-shaped and rotatably mounted to the hemming apparatus and according to the hemming method herein the circumference of the break plate is nested in the junction between the upward extension of the second panel and the inner surface of the flange portion, the first roller and the break plate grip the opposite sides of the flange portion and their movement causes downward folding of the flange portion.

The support frame includes an anvil or roller support and the first roller is manipulated by the robot-controlled arm to seat against and roll atop the anvil. The first roller is bi-conical and includes forward and rearward surfaces, each surface being frusto-conically shaped with the first surface being forwardmost and adapted to be brought to bear against and along the flange portion to fold the flange portion downwardly, at least in part, and the second surface being rearward and adapted to be supported and rolled in guiding relation atop the anvil.

The second roller is mounted for rolling movement atop the anvil and in either of three positions wherein the flange portion is gradually folded downwardly into a final hemmed relation. The second roller includes a cylindrical outer surface that is used to force the partially folded flange portion further downwardly and into a second position, a canted surface that functions first to pull the partially folded flange portion towards the mated upstanding edge portions and into a third position when the cylindrical body of the second roller is moved axially and second to complete a final downward folding of the flange portion when the body of the second roller and the geometric axis thereof is at an acute angle to the anvil.

In another preferred embodiment according to this invention, a method of roller hemming a pair of panel edges in face to face assembly by folding a flange portion adjacent an edge of a first panel over the top mated edge of a second panel, comprising the steps of securing a support housing to a manipulator; movably connecting a piston member to the support housing for controlled reciprocating movement along a first axis, movably connecting a carriage to the piston member for lateral movement along a second axis transverse to said first axis upon movement of the piston, said piston including first and second rollers for folding the flange portion and said carriage including opposite end sections and a break plate fixed to one end section, successively manipulating said support housing and actuating said piston whereby first to move the first roller and break plate into and from engagement with the flange portion and folding the flange portion, then to rotate the support housing and the rollers to position the second and first roller, respectively, into and away from association with the flange portion, and then moving the support housing and second roller relative to the flange portion in a manner to force the flange portion downwardly and against the second panel.

In this method, the steps include providing a support frame having an anvil that orients the workpiece in a manner that the panel edges project upwardly from the frame and form a guide path for the manipulator to follow, and guiding the support housing relative to the guide path and in a manner that each of the rollers is caused to engage the anvil when following the guide path.

In another preferred embodiment according to this invention, there is provided a roller-type hemming apparatus for attaching panel edges in face to face assembly by folding a flange portion adjacent an edge of one panel over a mated edge of another panel to form a hemmed panel assembly, the apparatus comprising:

a hemming carriage having at least one roller capable of completing a finished edge hem along the length of the mated edges of the panels wherein the flange portion of the first panel is folded over in a gradual bend from one end to another end of the mated edges to effectively engage the flange with an outer side of the mated edge portion of the second panel and thereby maintain the panels in an assembly, and

means for selectively positioning the roller relative to the panel assembly,

wherein said roller includes a cylindrical body, an annular rib, and a V-shaped annular groove between the body and the rib, the rib having a diameter greater than the diameter of the body and the groove having a canted surface that conjoins with the rib, the outer surface of the body being adapted to engage and force the flange portion vertically downwardly towards the panel assembly when the roller is in a first position, and the canted surface being adapted to both pull the flange portion towards the mated edges of the panels when the roller is pulled into a second position and force the flange portion against the second flange when the roller is rotated in a rigid body movement into a third position.

The roller-type hemming apparatus according to this embodiment of the invention further comprises:

a support housing having an upper end adapted to connect to a manipulator, a lower end, an interior passage opening on said lower end, and a piston including a slide shaft and a piston head, said shaft disposed for movement, at least in part, in said passage and said piston head disposed outside of said passage for movement away from and towards the support housing, said shaft and passage being disposed on a common geometrical axis,

said hemming carriage includes opposite end sections, a break plate mounted to one said end section for rotation relative thereto, a roller shaft having opposite ends, and a second roller, said roller shaft extending between said end sections and mounted in said piston head for axial up and downward movement therewith, and said rollers mounted to opposite respective ends of the roller shaft, said second roller being associated with said one end section and said break plate, and

means for mounting the hemming carriage to the slide shaft and atop the piston head, said means for mounting including a cam structure for connecting the hemming carriage to the support housing in a manner wherein outward extending and rearward retracting axial movement of the piston head, respectively, operates to drive the hemming carriage laterally of the slide shaft and into first and second positions.

The support housing and rollers are adapted to be rotated 180° relative to the axis of the slide shaft. Depending on the manipulator, such as the arm of a robotic machine, the first and second rollers are disposed in either of two positions for folding the flange portion, the first position positioning the second roller and break plate for folding engagement with the flange portion and the second position rotating the support housing and positioning the first roller into folding engagement with the flange portion to complete the hemming operation.

In regards to the first position of the support housing, the break plate and second roller are associated with the flange portion, the piston and carriage are substantially simultaneously moved, with the piston head moving between extended and retracted positions and the hemming carriage between its first and second positions, the carriage first position spacing the one end section of the carriage and the break plate thereon and the second roller from engagement with the flange portion, and the carriage second position sandwiching the flange portion between and into engagement with the second roller and the break plate.

In regards to the second position of the support housing, the break plate and second roller are rotated away and the first roller rotated into association with the flange portion, the piston and carriage are substantially simultaneously moved, causing the first roller to be forced downwardly, pulled axially in a manner that the canted surface engages the flange portion, and the roller body rotated in a manner that the rib and canted surface grip and fold the flange portion into final hemmed relation.

Preferably, the cam structure comprises securing at least one cam plate and associated cam finger to the support housing and forming in the hemming carriage a complementary cam slot for receiving the cam finger, the finger and slot being at an acute angle to the geometrical axis. Preferably, two cam plates (one on each side of the support housing) and two cam slots (one on each side of the carriage) are provided. The length of the cam fingers and cam slots and acute angles thereof determine the degree of lateral movement of the hemming carriage relative to the support housing.

Preferably, the break plate is in the form of a circular disk, wherein the outer circumferential edge thereof is adapted to engage and form a fulcrum bend line for the flange portion, and said first roller is bi-conical in shape and includes a forward frusto-conical surface that is adapted to engage the flange portion and a rearward frusto-conical surface adapted to be supported on a guide surface during a hemming operation.

Preferably, the hemming apparatus is adapted for operable connection to a work arm of a multi-axis robot. In this regard, the support housing has a mounting flange thereof fastened to the forward end of a manipulating robot hand.

Preferably, the piston head includes a transverse slide bore, and said hemming carriage includes a guide rod having opposite ends connected to the end sections and a medial portion slidably disposed in said slide bore, whereby said carriage may translate relative to the piston head.

Preferably, the first and second rollers are mounted to the guide rod and for rotation about a common axis.

Further, in another embodiment according to this invention there is disclosed a roll hemming apparatus, comprising: a support bed for supporting a workpiece having a pair of mated upturned panel edges with one panel edge including a flange portion that extends beyond and is adapted to be folded about the other panel edge, a support head having a piston and first and second rollers mounted to the piston, the support head fastenable to an industrial robot for sequentially moving the rollers along a movement path defined around the workpiece and engaging the rollers with the flange portion in a manner to fold the flange portion into engagement said other panel, a carriage member mounted to the piston for transverse movement thereto upon movement of the piston, the carriage having opposite first and second ends associated with said first and second rollers and a break plate on said first end, and a cam structure operating to selectively move the carriage member and associated break plate laterally of the piston head and towards and away from the first roller and into engagement with the flange portion depending on the direction of movement of the piston head.

For a more complete understanding of the present invention, reference is made to the following detailed description and accompanying drawings. In the drawings, like reference characters refer to like parts throughout the several views, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental side elevation view of a roller-type hemming head for hemming upturned panel edges nested on a support frame according to this invention, the hemming head having a flanged upper end secured to the end of a programmed robot hand and a lower end positioned above the panel edges and moved by the robot in a manner that rollers in the hemming head join the panel edges;

FIGS. 2A-2F show the hemming head according to this invention, wherein FIG. 2A is an axial plan view looking upwardly at the lower end of the hemming head as seen in FIG. 1, FIGS. 2B and 2C are side elevation views showing a cam structure on two opposite sides of the hemming head, FIG. 2D is a side elevation view seen 90° from the views of FIGS. 2B and 2C, and FIGS. 2E and 2F are perspective views looking rearward from the lower end of hemming end and showing the cam structure of FIGS. 2B and 2C;

FIG. 3 is a side elevation view, similar to FIG. 2B, showing the cam structure, a piston having a slide shaft and piston head mounted to the hemming head for relative vertical movement thereto, and a roller carriage mounted to the piston head for relative transverse movement thereto;

FIG. 4 is a partial cutaway view of the assembly of FIG. 3 showing the hemming head, the slide shaft of the piston disposed in a central passage of the hemming head, and the piston head disposed for movement towards and away from the lower end of the hemming head;

FIG. 5 is an exploded assembly view of the roller carriage, the piston including the slide shaft and piston head thereof, and the hemming head;

FIG. 6 is a side elevation view showing a pair of panels with the edges upturned, mated in nested relation and positioned for hemming, and a preferred succession of steps taken according to this invention used in hemming the panels;

FIGS. 7 and 8 are perspective and side elevation views of the first step in the hemming method according to this invention;

FIGS. 9, 10, and 11 are side elevation views of the second, third, and fourth steps, respectively, in the hemming method according to this invention;

FIG. 12 is a perspective view of the pre-hemming roller and the break plate cooperating to form a J-flange according to a preferred embodiment of this invention; and

FIG. 13 is a perspective view of a hemmed-edge connection including a J-flange according to a preferred embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The joining of a pair of panel edges by hemming is conventional and described herein by way of providing background as to the application of the hemming operation using the hemming apparatus 10 according to the invention herein. Further, the robot machine, including the robot arm and the robot hand, are also well known in the art and their description is omitted.

Referring now to the drawings, FIG. 1 is an environmental elevation view of a roller-type hemming apparatus 10 according to this invention positioned above a support frame 12 that is adapted to support a workpiece W. The hemming apparatus 10 includes a hemming head 14 that is operably connected to a work arm, such as provided on a multi-axis controllable robot hand, and is constrained for movement along a predetermined travel path around the frame 12 and relative to the workpiece W. The frame 12 is configured to nest or otherwise support the specific workpiece and includes a support anvil 16 that supports a roll hemmer of the hemming apparatus 10 during the hemming operation, as will be described herein below. The robot is not shown, as it is conventional and known to those having ordinary skill in the art.

The workpiece W may comprise, for example, metal panels which are joinable along corresponding outer edges or perimeters of the respective panels to form an automobile door, hood, trunk, sunroof, or deck lid. Preferably, the invention herein is described in regards to an automobile sunroof.

Referring to FIG. 6, the sunroof is formed from the assembly of an outer metal panel W_(o) and an inner metal panel W_(i). The panels W_(o) and W_(i) are in nested relation with one another atop the frame 12 and have upturned edge portions 18 and 20, respectively, in mated faced engagement with one another. The upturned edge portion 18 of the outer panel W_(o) engages the upturned edge portion 20 of the inner panel W_(i) and forms a flange portion 22 that extends across and beyond the upturned edge 24 of the inner panel W_(i), the flange portion 22 terminating in an upturned edge 26.

Initially, the upturned edge portion 18 (and flange portion 22 thereof) is bent upwardly and substantially at a right angle to the plane of the outer panel W_(o). In addition the upturned edge portion 20 is bent upwardly and substantially at a right angle to the plane of the inner panel W_(i). The peripheral or upturned edge 24 of the inner panel W_(i) is disposed approximately midway of the upward extension of the outer upturned edge portion 18. The upturned flange portion 20 has outer and inner surfaces 20 a and 20 b, wherein the outer surface 20 a is abutted against the upturned edge portion 18.

A series of four folding steps is shown in FIG. 6, wherein the flange portion 22 is incrementally bent or folded downwardly and against the surface 20 b and the upturned edge portion 20 is securely gripped between the lower part of the edge portion 18 and the flange portion 22.

Referring to FIGS. 2A-2F, 3, and 4, the hemming head 14 includes an axially elongated support housing 28 having upper and lower ends 28 a and 28 b and opposite sides 28 c and 28 d at the lower end 28 b, a piston 30 including a slide shaft 32 and a piston head 34, and a roller or hemming carriage 36. The support housing 28 has the upper end 28 a thereof including a mounting flange 38 for connecting the support housing 28 to the robot and includes a central passage 40 for receiving and guiding the slide shaft 32. The guide passage 40 opens on the lower end 28 b to permit the slide shaft 32, at least in part, to extend from and retract into the support housing 28.

While not shown, pressure source and control circuits are operably associated with the piston 30 to move the slide shaft 32 and associated piston head 34 in opposite axial directions, toward and away from the support housing 28.

As shown in FIG. 5, the slide shaft 32 comprises an axially elongated body having rearward and forward ends, 32 a and 32 b, respectively, and the piston head 34 is joined to the forward end 32 b. The slide shaft 32 and central passage 40 are complementary to one another and have substantially identical square cross-sections. The cross-section of the slide shaft 32 is slightly smaller than the cross-section of the passage 40 to permit sliding movement of the slide shaft 32 in the support housing 28. The cross-sections of the passage 40 and the slide shaft 32 are generally square in shape to prevent anything other than the axial movement of the shaft 32 relative to the passage 40. The rearward end 32 a of the slide shaft is formed to include a lock recess 33 that connects to a drive mechanism (not shown) in the support housing 24. A supply of pressure and the drive mechanism causes the slide shaft 32 to slide in the passage 40 and the piston head 34 to extend away from or retract towards the lower end 28 b of the support housing 24, as desired. The piston head 34 is formed with a pair of mounting bores 42 and a central guide bore 44. The bores 42 and 44 extend through the piston head 36 in a direction transverse to the common central geometric axis “A” of the shaft body to which the piston head 34 is joined and the central passage 40.

The roller carriage 36 includes a backup carriage 46 which is coupled to the slide shaft 32 and connected via a cam structure 47 to the support housing 28. The backup carriage 46 comprises a generally rectangular body or plate 54 having generally planar upper and lower surfaces 54 a and 54 b, opposite end walls 54 c and 54 d, opposite sidewalls 54 e and 54 f, a central rectangular guide slot 56 that is approximately centered between the walls 54 c-54 f and extends between the surfaces 54 a and 54 b, and a pair of like-shaped guide flanges 58. The central guide slot 56 is adapted to fit about the cross-section of the slide shaft 32 and seat the backup carriage 46 atop the piston head 34. The guide slot 56 and cam structure 47 cooperate to force the backup carriage 46 to slide laterally across the piston head 34.

The guide flanges 58 project downwardly from the lower surface 54 b. The guide flanges 58 are proximate to the opposite end walls 54 c and 54 d of the plate 54. Each guide flange 58 is formed to include an arched central surface 57 and a pair of slide bores 59. The pair of slide bores 59 in the guide flange 58 proximate to the end 54 c are aligned with the respective pair of slide bores 59 in the guide flange 58 proximate to the end 54 d.

The guide shafts 48 are axially elongated, generally cylindrical, and have opposite ends 48 a and 48 b. The guide shafts 48 are sized to extend between the guide flanges 58 and have their respective ends 48 a and 48 b received within the slide bores 59 and secured to the opposed guide flanges 58. The guide shafts 48 are also passed through respective of the mounting bores 42 in the piston head 34 and constrain the backup carriage 46 for transverse sliding movement relative to the piston head 34.

Importantly, the cam structure 47 is provided to drive the backup carriage 46 transversely relative to the piston head 34 substantially simultaneously with axial reciprocating movement of the slide shaft 32 and extension and retraction of the piston head 34 away from and towards the lower end 28 b of the support housing 28. In this regard, the cam structure 47 associates a pair of cam plates 60 with a pair of cam slots 62. The cam slots 62 are formed in the opposite lateral longitudinally extending sidewalls 54 e and 54 f of the backup plate 54. Further, each cam slot 62 opens on the upper surface 54 a of the backup plate 54 and angles downwardly therefrom and towards the lower surface 54 b of the backup plate 54.

The cam plates 60 are mounted, respectively, on one and the other side 28 c and 28 d of the support housing 28 and each includes a cam finger 64. When mounted, the cam fingers 64 angle downwardly from the lower end 28 b of the support housing 28 and in a manner to be slidingly received in a cam slot 62 in the backup plate 54 therebelow. The cam slots 62 and fingers 64 are of like generally rectangular shape and complementary with one another such that the opposite edges of each rectangular shaped cam finger 64 engages and makes sliding contact with the opposing surfaces that define the associated rectangular shaped cam slot 62.

As shown in FIG. 3, when the slide shaft 32 is in an upward (i.e., retracted position), the lower edge of the cam plate 60 is juxtaposed with the upper surface 54 a of the backup plate 54. When the slide shaft 32 is extended, as shown in FIG. 1, the assembly of the piston head 34 and the roller carriage 36 is driven downwardly and away from the support housing 24, and the cam fingers 62 and cam slots 60 operate to drive the backup carriage laterally of the central axis “A” of the housing.

Preferably, as shown best in FIG. 2, two cam plates 60 and associated cam slots 62 are provided. The cam plates 60 and associated cam fingers 64 are oriented 180° to one another and on opposite sides 28 c and 28 d of the hemming support housing 28. The symmetrical arrangement ensures smooth and wobble-free axial reciprocating movement of the slide shaft 32 and smooth transmission of hemming forces. However, depending on the particular application, a single cam slot and finger, if appropriately dimensioned and configured, may be sufficient.

As seen best in FIGS. 3-5, the roller assembly 50 is associated with the slide shaft 32 and the roller carriage 36 and includes a cylindrical roller bearing cartridge 66, a roller shaft 68 having opposite ends 68 a and 68 b, a pre-hemming roller 70, and a hemming roller 72.

The roller bearing cartridge 66 is disposed in the guide bore 44 that extends through the piston head 34. The roller shaft 68 is journaled for rotation in the bearing cartridge 66 and the opposite ends 68 a and 68 b are dimensioned to be disposed proximate to the guide flanges 58 and be circumposed by the arched central surfaces 57 of the respective guide flanges 58 proximate thereto. The roller shaft 68 and bearing cartridge 66 do not translate relative to the piston head 34. The entire length of the roller shaft 68 does not need to have a consistent diameter, and the opposite ends 68 a and 68 b of the roller shaft 68 can be tapered or stepped to varying diameters.

The roller assembly 50 also includes the first or pre-hemming roller 70 which is generally bi-conical and has rearward and forward ends, 70 a and 70 b, and rearward and forward surfaces, 74 and 76, respectively. The rearward and forward surfaces, 74 and 76, are centered on a central geometric axis “B” and conjoin with one another to form a circumferential V-shaped peak 78. The rearward and forward surfaces 74 and 76 are frusto-conical and converge radially inwardly from the peak 78 towards the respective rearward and forward ends 70 a and 70 b. The rearward end 70 a is adapted to be secured to the distal end 68 b of the roller shaft 68 for coaxial rotation thereto. So secured, the pre-hemming roller 70 is proximate to the endwall 54 c of the backup carriage plate 54 and circumposed, in part, by the guide flange 58 disposed proximate thereto. The forward end 70 b of the pre-hemming roller 70 is formed with a central cylindrical socket 70 c and is associated with the backup roller assembly 52, in a manner to be described herein below.

The roller assembly 52 also includes the hemming roller 72 which is generally cylindrical and has rearward and forward ends 72 a and 72 b and an annular V-shaped forming groove 80 between the ends 72 a and 72 b. The V-shaped forming groove 80 is positioned proximate to the forward end 72 b. The hemming roller 72 also includes a cylindrical outer surface 82 which extends from the rearward end 72 a to the forming groove 80, and an annular rib 84 at the forward end 72 b. The V-shaped forming groove 80, outer surface 82, and annular rib 84 are generally centered on the central geometric axis “B” of the hemming roller 72. The rearward end 72 a of the hemming roller 72 is adapted to be secured to the end 68 b of the roller shaft 68 for coaxial rotation thereto. So secured, the forward end 72 b of the hemming roller 72 is proximate to the endwall 54 d of the carriage plate 54 and circumposed, in part, by the guide flange 58 disposed proximate thereto.

As shown in FIG. 3, the forming groove 80 is formed by angled bevels, or canted sidewalls, 80 a and 80 b, which converge to form a V-shape and conjoin to form an annular transition root 80 c. The annular rib 84 and associated canted sidewall 80 b are slightly greater in diameter than that of the outer surface 82 and associated canted sidewall 80 a. Further, the canted sidewall 80 b is less steeply angled than the canted sidewall 80 a. The annular forming groove 80 and annular rib 84 are radially dimensioned and angled to provide hemming of the upturned flange portion 22 about the upturned edge portion 20.

As will be discussed herein below, and shown in FIGS. 9-13, the rollers 70 and 72 bend the upturned edge portion 18 to form the flange portion 22 and bend the flange portion 22 downwardly relative to the upturned edge portion 20. The hemming roller 72 uses the forming groove 80, canted surface 80 b, and rib 84 to pull the flange portion 22 towards the upturned flange 20. The hemming apparatus 10 is then manipulated by the robot, the hemming head 70 rotated, and the rib 84 and canted surface 80 b cooperate to fold the flange portion 22 towards and into gripping relation against the upturned inner flange 20.

The backup roller assembly 52 is used in conjunction with the pre-hemming roller 70 and includes a support link 86 and a hat-shaped roller assembly 88. The support link 86 includes a link body 90 and a link arm 92, the link body 90 and link arm 92 being at an angle to one another. The link body 90 is secured to the end wall 54 c of the backup plate 54 in a manner that the link arm 92 angles downwardly and away from the lower surface 54 b of the backup plate 54 and towards the guide flange 58 proximate to the end 54 c.

The hat-shaped roller assembly 88 includes a cylindrical roller 94 and a thin rigid cylindrical disk or break plate 96 having upper and lower surfaces, 96 a and 96 b, and an outer circumferential edge 96 c. The hat-shaped roller assembly 88 further includes a canted break surface 95 which extends from the lower surface 96 b to the cylindrical roller 94. The roller 94 and break plate 96 are in coaxial relation with one another and the break plate 96 is greater in diameter than the diameter of the roller 94.

The hat-shaped roller assembly 88 is attached to the link arm 92 in a manner such that the lower surface 96 b of the break plate 96 is juxtaposed with the forward frusto-conical surface 76 of the pre-hemming roller 70, and the roller 94 and distal end of the link arm 92 are juxtaposed with and disposed, at least in part, in the socket 70 c of the pre-hemming roller 70. Preferably, the lower surface 96 b of the break plate 96 and frusto-conical forward surface 76 of the pre-hemming roller 70 are generally at the same acute angle when the backup roller assembly 52 is mounted to the carriage plate 46. As will be described in further detail below, the hat-shaped roller assembly 88 and the brake plate 96 cooperate to form the flange portion 22. Preferably, the hat-shaped roller assembly 88 and the pre-hemming roller 70 cooperate to form a J-flange 21, such as shown in FIG. 12.

Turning to FIG. 6, the steps of the hemming operation are generally shown, with the hemming apparatus 10 being omitted for purposes of illustration. The workpieces are supported on the frame 12 with the upturned flange portions 18 and 22 in mated relation to one another and proximate to the anvil 16. The upturned edge portion 18 of the outer plate W_(o) is first bent to form the flange portion 22, which is approximately at an angle of 30° to a vertical to the lower end of the panel edge portion 18. Thereafter, the flange portion 22 is progressively and incrementally folded downwardly and inwardly toward the inner panel edge portion 20, first by forcing the flange portion 22 downwardly to about 90° to the vertical, then folding the flange portion 22 towards the inner panel edge portion 20 to about 120° to the vertical, and then forcing the flange portion 22 against the inner panel edge portion 20 to about 180° to a vertical through the panel edge portion 18.

The folding of the flange portion 22, or the hemming, is accomplished by the robot following a prescribed path in connection with the support frame 12 and anvil 16, as well as manipulation of the hemming carriage 36 and positioning of the rollers 70 and 72.

In particular, and in the hemming operation according to an embodiment of the invention herein, reference is drawn to FIGS. 7-11.

In a first pass, the robot arm positions the pre-hemming roller 70 relative to the support frame 12 and the upturned edge portions 18 and 20 of the workpiece panels.

The slide shaft 32 is extended from the support housing 28 and the piston head 34 is extended away from the lower end 28 b thereof. As illustrated in FIG. 1, the cam structure 47 causes the roller carriage 36 to laterally move relative to the piston head and the hemming roller 70 to move laterally away from the break plate 96. The pre-hemming roller 70 and break plate 96 are positioned about the upturned edge portions 20 and 22, and the frusto-conical surfaces 74 and 76 of the hemming roller 70 positioned above the anvil 16 and juxtaposed with the upward extension of the panel edge portion 20.

As shown in FIGS. 3, 4, 7, and 8, the slide shaft 32 and piston head 36 are retracted, and the cam structure 47 moves the pre-hemming roller 70 towards the backup assembly 52. The bi-conical surfaces 74 and 76 of the roller 70 are thus rotatably seated on the anvil 16 and against one side of the upturned panel edge portion 18, and the outer circumference 96 c of the break plate 96 is positioned on the other side of the edge portion 18 and atop the edge 24 of the panel edge portion 20. The break plate 96 and frusto-conical surface 76 of the pre-hemming roller 70 define a fulcrum to bend the panel edge portion 18.

As shown in the preferred embodiment in FIG. 12, the hat-shaped roller assembly 88 and the pre-hemming roller 70 cooperate to form the J-flange 21. The J-flange 21 includes a medial bend portion 23 and a distal end portion 25. The medial bend portion 23 is formed between the canted break surface 95 and the forward end 70 b of the pre-hemming roller 70. The distal end portion 25 is formed between the cylindrical roller 94 and the socket 70 c and forward end 70 b of the pre-hemming roller 70.

The robot then moves the hemming apparatus 10 along a predetermined path, defined by the flanges 18 and 20, with the angled surface 76 of the pre-hemming roller 70 bending the upward extension of the edge portion 18 approximately 30° to form a flange portion 22.

As shown in FIG. 3, when the piston is retracted, the piston head 34 is snug against the cam plate 60 and the pre-hemming roller 70 juxtaposed with the backup roller assembly 52 and the break plate 96 thereof.

As shown in FIG. 7, the hemming apparatus 10 progressively bends the upturned edge to form the angled flange portion 22.

Referring to FIG. 9, in the next and second pass, the piston head 34 is extended, and the cam structure 47 causes the pre-hemming roller 70 to move from engagement with the flange portion 22, the support housing 28 is lifted and rotated 180° by the robot, and the hemming roller 72 is rotated into position proximate to the partly folded flange portion 22.

The piston 30 and slide shaft 32 are retracted, thereby spacing the hemming roller 72 away from the guide flange 58 associated with the plate end 54 d.

The robot then lowers the support housing 28 and associated hemming roller 72 downwardly and the surface 82 of the hemming roller 72 partially in supported relation against the anvil 16 and partially against the flange portion 22, with the downward lowering and traversing movement of the robot causing the flange portion 22 to progressively fold downwardly and be approximately 90° to the upturned edge portion 18.

Referring to FIG. 10, in the next and third pass, the piston 30 and associated piston head 34 are partially retracted, at least in part, and the cam structure 47 causes the hemming roller 72 to be pulled axially towards the end 54 d of the carriage plate 54. As a result of this axial pulling by the hemming roller 72, the canted surface 80 b of the forming groove 80 is forced against the flange portion 22, causing the flange portion 22 to be folded further downwardly towards the upturned edge portion 20. The robot then moves the roller 72 on the anvil 16 and the canted surface 80 b of the V-shaped shaped groove 80 about the workpiece. The operation further bends the flange portion 22 towards the panel 20 to a position approximately 120° to a vertical.

Referring to FIG. 11, in a final and fourth pass, the robot rotates the hemming apparatus 10 and the roller carriage 36 thereon by an appropriate amount to cause the canted surface 80 b of the V-shaped forming groove 80 to rotate and force the flange portion 22 downwardly and against the upturned edge portion 20 of the inner panel 20. The robot then moves the hemming roller 72 on the anvil 16 and about the workpieces W_(o) and W_(i), whereupon the flange portion 22 is folded against the panel edge portion 20 and the panel portion 20 is sandwiched between the upper and lower halves of the upturned edge portion 18 and to be held in firm gripped engagement. The flange portion 22 completes the hemming operation. In this fourth pass, the flange portion 22 has been bent approximately 180° from its original position.

When a J-flange 21 is formed by the hat-shaped roller assembly 88 and the pre-hemming roller 70 according to the first pass, a hemmed-edge connection, such as shown in FIG. 13, is created. In this preferred embodiment, the V-shaped forming groove 80 operates to form the medial bend portion 23 and the distal bend portion 25 down and against the workpiece W_(i) and the upturned edge portion 20, thereby significantly increasing the strength of the hemmed-edge connection between the workpieces.

Desirably, in operation, should one or both of the hemming rollers 70 and 72 need replacement, either for repair or to install a different roller having another diameter and for use in another hemming application, the rollers are easily removable and changed for the desired needs.

As is apparent from the preceding, the present invention provides a roller-type hemming apparatus for edge hemming vehicle closure panels, such as hemming door, hood, trunk, and deck lid panels. 

1. A method for roller hemming together the edges of at least two metal panels to form an edge-hemmed connection between the panels, the steps of the method comprising: positioning the edges in mated faced engagement on a support frame, the edge of the first metal panel engaging the edge of the second metal panel such that the edge of the first metal panel forms a flange portion that extends beyond the mated edge of the second metal panel; providing a hemming apparatus having a first roller, a second roller, and a break plate, the break plate being associated with the first roller, the first roller having a first canted surface, and the first and second rollers being rotatably secured to the hemming apparatus; manipulating the hemming apparatus in a manner that the first roller and the break plate engage opposite sides of the first metal panel and form a bend line on the flange portion by moving the first roller and the break plate along the length of the mated edges of the metal panels wherein the flange portion of the first metal panel is folded over in a gradual bend to form the bend line; and manipulating the hemming apparatus in a manner that the second roller engages the flange portion and moves along the length of the mated edges of the metal panels in at least one successive pass to force the flange portion to bend about the bend line toward and into engagement with the second metal panel to form an edge-hemmed connection between the panels.
 2. The method of claim 1 wherein the second roller includes a cylindrical outer surface that engages and forces the flange portion downwardly during one of the at least one successive passes along the length of the mated edges.
 3. The method of claim 2 wherein the second roller includes a head portion having a canted surface that engages and forces the flange portion downwardly during one of the at least one successive passes along the length of the mated edges.
 4. The method of claim 3 which comprises manipulating the hemming apparatus in a manner that the canted surface of the second roller moves from a first angular position with respect to the mated edges of the metal panels to a second angular position with respect to the mated edges of the metal panels, and wherein, while the second roller is in the second angular position, the second roller engages and forces the flange portion downwardly and against the second metal panel during one of the at least one successive passes along the length of the mated edges to form an edge-hemmed connection between the panels.
 5. The method of claim 4 wherein the hemming apparatus comprises a cam structure to selectively move the break plate between an open position and an engaged position, and the first roller and the break plate of the hemming apparatus are manipulated to engage the opposite sides of the first metal panel by ensuring that the break plate is in the engaged position, positioning the first roller such that a base of the first canted surface is proximate to a base of the flange portion such that the first roller forces the flange portion to a bent position, and engaging the cam structure to move the break plate from the open position to the engaged position such that the break plate and the first roller clamp the flange portion to create the bend line at the base of the flange portion.
 6. The method of claim 1 wherein the hemming apparatus comprises a cam structure to selectively move the break plate between an open position and an engaged position, and the first roller and the break plate of the hemming apparatus are manipulated to engage the opposite sides of the first metal panel by ensuring that the break plate is in the engaged position, positioning the first roller such that a base of the first canted surface is proximate to a base of the flange portion such that the first roller forces the flange portion to a bent position, and engaging the cam structure to move the break plate from the open position to the engaged position such that the break plate and the first roller clamp the flange portion to create the bend line at the base of the flange portion.
 7. The method of claim 6 wherein the second roller includes a cylindrical outer surface that engages and forces the flange portion downwardly during one of the at least one successive passes along the length of the mated edges.
 8. The method of claim 7 wherein the second roller includes a head portion having a canted surface that engages and forces the flange portion downwardly during one of the at least one successive passes along the length of the mated edges.
 9. The method of claim 8 which comprises manipulating the hemming apparatus in a manner that the canted surface of the second roller moves from a first angular position with respect to the mated edges of the metal panels to a second angular position with respect to the mated edges of the metal panels, and wherein, while the second roller is in the second angular position, the second roller engages and forces the flange portion downwardly and against the second metal panel during one of the at least one successive passes along the length of the mated edges to form an edge-hemmed connection between the panels.
 10. A roller-type hemming apparatus for attaching panel edges in face to face assembly by folding a flange portion adjacent an edge of one panel over a mated edge of another panel to form a hemmed panel assembly, the apparatus comprising: a roller assembly having at least one roller capable of completing a finished edge hem along the length of the mated edges of the panels wherein the flange portion of the first panel is folded over in a gradual bend from one end to another end of the mated edges to effectively engage the flange with an outer side of the mated edge portion of the second panel and thereby maintain the panels in an assembly, a first roller including a cylindrical body, an annular rib, and a groove between the body and the rib, the rib having a diameter greater than the diameter of the body and the groove having a canted surface that conjoins with the rib, the outer surface of the body being adapted to engage and force the flange portion vertically downwardly towards the panel assembly when the first roller is in a first position, and the canted surface being adapted to both pull the flange portion towards the mated edges of the panels when the first roller is in a second position, and force the flange portion of the first panel against the mated edge portion of the second panel when the first roller is rotated in a rigid body movement in a third position.
 11. The roller-type hemming apparatus of claim 10 which comprises: a support housing having an upper end adapted to connect to a manipulator, a lower end, an interior passage opening on the lower end, and a piston including a slide shaft and a piston head, the slide shaft disposed for movement within the interior passage, and the piston head disposed outside of the interior passage for movement away from and towards the support housing, the slide shaft and interior passage being disposed on a common geometrical axis; a hemming carriage having opposite end sections and a break plate secured to one of the end sections for rotation relative thereto; and the roller assembly further including a roller shaft having opposite ends and a second roller, the roller shaft secured within the piston head for axial up and downward movement therewith, and the first and second rollers mounted to opposite respective ends of the roller shaft.
 12. The roller-type hemming apparatus of claim 11 which comprises: a cam structure for connecting the hemming carriage to the support housing and atop the piston head in a manner wherein outward extending axial movement of the piston head operates to drive the hemming carriage laterally of the slide shaft and into a first position, and rearward retracting axial movement of the piston head operates to drive the hemming carriage laterally of the slide shaft into a second position.
 13. The roller-type hemming apparatus of claim 12 wherein the cam structure comprises at least one cam plate and associated cam finger secured to the support housing and forming in the hemming carriage a complementary cam slot for receiving the cam finger, the cam finger and cam slot being at an acute angle to the geometrical axis, wherein the length of the cam finger and cam slot and the degree of the acute angle thereof determines the amount of lateral movement of the hemming carriage relative to the support housing.
 14. The roller-type hemming apparatus of claim 13 which comprises: two cam plates, each cam plate being disposed on a respective opposite side of the support housing to each other, and two cam slots, each of the cam slots being associated with a respective one of the cam plates.
 15. A hemming head configured for attachment to a robot for performing a hemming operation, the hemming head comprising: a support housing adapted for securement to the robot arm on a first end, and including a first roller rotatably secured to the support housing, the first roller including a cylindrical body, a head having a diameter greater than the body, and a groove between the body and head, the groove having a diameter less than the body and having a canted surface that conjoins with the head.
 16. The hemming head of claim 15 wherein the cylindrical body is adapted to engage and force a workpiece edge downwardly to a first position and the canted surface is adapted to engage and force the workpiece from the first position to a second position.
 17. The hemming head of claim 15 comprising a second roller rotatably secured to the support housing, and a hemming carriage having opposite end sections and a break plate secured to one of the end sections for rotation relative thereto.
 18. The hemming head of claim 17 comprising a piston including a slide shaft and a piston head, the slide shaft disposed for movement within an interior passage of the support housing, and the piston head disposed outside of the interior passage for axial movement relative to the support housing, the slide shaft and interior passage being disposed on a common geometrical axis, and the first roller being rotatably secured to the piston head.
 19. The hemming head of claim 18 which comprises: a cam structure for connecting the hemming carriage to the support housing and atop the piston head in a manner wherein outward extending axial movement of the piston head operates to drive the hemming carriage laterally of the slide shaft and into a first position, and rearward retracting axial movement of the piston head operates to drive the hemming carriage laterally of the slide shaft into a second position.
 20. The hemming head of claim 19 wherein the cam structure comprises at least one cam plate and associated cam finger secured to the support housing and forming in the hemming carriage a complementary cam slot for receiving the cam finger, the cam finger and cam slot being at an acute angle to the geometrical axis. 